Fertilizer applied today could still be there in 2093, scientists report October 21 in the Proceedings of the National Academy of Sciences. The study is the first to measure how long nitrogen-based fertilizers persist in the field.

In 1982, a team led by Mathieu Sebilo of the Université Pierre et Marie Curie in Paris infused soil with fertilizer containing nitrogen-15, a form of the element uncommon in nature. The next year, the researchers found that crops had absorbed around half of the fertilizer, with most of the rest taken up by microorganisms and released back into the soil.

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